It is said that nature abhors a vacuum, and if proof were
needed then our partly built pond would provide it. Filled only with clean rainwater, it had many
aquatic bugs in it even before we introduced a few plants into it. One of the most notable visitors to the pond
was a large emperor dragonfly which spent much time laying eggs into the
pondweed. This was several weeks ago,
but already I have seen dragonfly larvae swimming about in there. I have heard it said that dragonflies only
live for a few weeks, but that refers only to the adults. The larvae will lurk on the bottom of a pond
for two or three years until the weather is fit for them to emerge as beautiful
and aerobatic predators. The larvae are powerful predators that will eat
anything from water fleas to small fish.
The adults are also agile predators that will take any flying insect,
including smaller dragonflies.
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| Emporer Dragonfly (Female) |
We caught sight of another aerial predator recently as a
sparrowhawk flew over ignoring, and ignored by several seagulls as it flew
past. It was also ignored by a large
gathering of house-martins and swallows that were flying round the house and
landing on neighbouring roofs or telegraph wires. Swallows and martins have nothing to fear
from sparrowhawks which are neither fast enough nor agile enough to catch them. Sparrowhawks method of catching prey is to
use surprise, which they do by swooping low over hedges and fences, taking the
prey while it is still perched in a bush or tree. Swallows and martins are preyed on by a much
more agile bird – the hobby, which will accompany swallows and martins as they
migrate to Africa. We assume that the
gathering of martins and swallows was to do with migration which they won’t
start until the flock is large enough. A
large flock of birds constantly shifting position within the flock confuses
predators and just on numbers alone reduces the chance of an individual bird
being taken.
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| Sparrowhawk (Male) |
Birds of prey are almost defined by their prey and their
hunting methods. Sparrowhawks swoop,
hobbies use sheer speed, and peregrines use that amazing vertical dive at
nearly 200 miles an hour. But there are
many birds of prey that adopt more sedate methods. Walk around Rye Harbour reserve and you are
almost certain to see a kestrel hovering and keeping perfectly still waiting
for a mouse or vole to stray into the open, the kestrel alerted to its presence
by urine trails that reflect ultra-violet light. The barn owl doesn’t quite hover, but moves very
slowly above the ground, relying on silent flight and pale colours to hide it
from its prey.
Larger raptors like marsh harriers or buzzards are able to
take larger prey like rabbits or weasels which are generally slower moving and
easier to see. They use a swift pounce
from slow soaring flight to secure their prey.
One of our largest raptors and one that you are increasingly likely to
see in this area is the successfully reintroduced red kite. How does that catch its prey? Well, it doesn’t. It is not a bird of prey, it is a scavenger
that, when it is not being overfed by farmers in Wales that charge the public to
see them, will take carrion or any other scraps it can find. The red kite reintroduction has been so
successful, that it makes you wonder why it became extinct in the first
place. Perhaps it was persecution by
those same farmers who mistakenly saw it as a threat to their livestock.
